【作者】 Chegeni Alireza；

【导师】 刁其玉；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2013， 博士

【摘要】 本试验旨在研究以玉米秸秆为粗料的绵羊日粮中添加多聚物包被尿素以及膨润土对绵羊生产性能的影响。试验一：采用4只装有瘤胃瘘管的杜泊×小尾寒羊杂交羯羊,按照4×4拉丁方试验,研究以玉米秸秆为主的粗料型日粮中添加多聚物包被尿素(Optigen Ⅱ)以及膨润土对绵羊采食量、营养物质消化率、氮沉积、瘤胃发酵以及微生物蛋白质合成量的影响。试验羊只单栏独饲,每期试验持续24天,包括14天的适应期以及10天的采样期(第l到5天进行消化代谢试验,第6天羊只休息,第7天采瘤胃液,第8到10天进行尼龙袋试验),消化代谢试验开始前4天将试验羊只上代谢笼进行环境适应。试验设计了4种等氮等能日粮,均含60%玉米秸秆和40%精料(干物质基础)。各处理间精料组成均不同：对照组(CON)包含大麦、麸皮和豆粕；多聚物包被尿素(PCU)组包含大麦、麸皮、玉米和Optigen;豆粕添加组(SB)在CON基础上额外补充2%的豆粕；多聚包被尿素-豆粕组(PCUSB)在PCU基础上额外补充2%的豆粕。试验数据按4×4拉丁方数据,使用SAS的MIXED模型(SAS,1999)进行方差分析。试验结果表明,PCU组的有机物(OM)表观消化率(P=0.03)、真消化率(P=0.04)和氮消化率(P<0.01)显著高于CON和SB组,氮的消化率在PCU组要高于CON、SB和PCUSB组(P<0.01),在SB和PCUSB组也要高于CON组,但干物质采食量(DMI)和其他营养物质消化率无显著差异。SB组的羊只仅氮消化率发生了改变。日粮处理并未影响氮采食量、尿氮排出量,但PCU组的粪氮排出量有下降趋势(P=0.09),氮沉积有上升趋势(P=0.09)。另外,尿嘌呤衍生物(PD)和微生物氮产量未受日粮处理的影响。PCU组的瘤胃液丙酸浓度显著升高(P<0.01),但额外补充豆粕并未改变该比例。瘤胃pH和总挥发性脂肪酸(VFA)均不受日粮处理的影响。PCU组的瘤胃液氨氮水平持续上升,在饲喂后3小时达到峰值,并持续7小时。PCU和SB组的玉米秸秆24小时干物质消化率显著高于CON组,48小时干物质消化率显著高于CON或PCUSB组(P<0.01)；CON组的干物质消化率在72小时最低(P<0.05)。PCU和SB组的DM有效降解率显著高于其他组(P<0.05)。由此可见,Optigen作为一种新型的非蛋白氮饲料代替豆粕,能够提高绵羊对粗料型日粮OM和氮的消化率以及有效降解率。尽管SB组提高了有效降解率,但除氮之外并未影响其他营养物质的消化率,Optigen中添加豆粕并未提高营养物质消化率、氮沉积、微生物氮合成量、瘤胃发酵以及玉米秸秆的有效降解率。试验二：材料和方法同试验一,设计4种高精料型等能等氮日粮,含60%精料和40%玉米秸秆(干物质基础)。结果表明,SB和PCUSB组的OM表观消化率显著低于其他组(P=0.06),SB组的氮(P=0.02)和OM(P=0.04)真消化率显著低于其他组。SB和PCUSB组氮沉积(P=0.03)和瘤胃微生物氮产量(P=0.03)显著低于CON组。SB组瘤胃氨氮水平(P=0.03)显著低于其他各组。PCUSB组的瘤胃总VFA(P=0.052)高于CON组,且与其他组相比,显著降低了瘤胃液乙酸比例(P=0.03)和乙酸：丙酸的比例(P=0.01),增加了丙酸比例(P=0.02)和戊酸比例(P<0.02)。PCU组瘤胃液氨氮水平上升,在饲喂后3小时达到最高水平,并持续9小时。以Optigen代替豆粕对饲喂高精料日粮绵羊的营养物质消化率、微生物氮、瘤胃发酵指数和有效降解率并无副作用,然而在Optigen中额外添加豆粕并未提高营养物质消化率、氮沉积、微生物氮和玉米秸秆的有效降解率,同时降低了乙丙比。试验三：本试验旨在研究不同水平Optigen替代豆粕对舍饲羔羊采食量、生长性能和血液生化指标的影响。试验选用64只杜寒杂交羔羊[27±3.3(s.d.)kg],采用完全随机试验设计分为四个处理组,每组包含4个圈舍,每个圈舍4只羔羊。设计4种含60%精料和40%玉米秸秆(干物质基础)的等氮(CP=13.5%)等能(ME=8.2Mj/kg)日粮,并以0%(PCUO)、33%(PCU33)、67%(PCU67)和100%(PCU100)的Optigen替代豆粕,试验期70天。结果表明,以33%和67%的Optigen代替豆粕对干物质采食量无影响,但PCUl00组显著降低了干物质采食量(P=0.04)。PCU33组和PCUO组的日增重不差异,但随Optigen替代水平的增加,日增重显著降低(P<0.01),因此与PCUO组相比,增重/饲料消耗的比例(G/F)在PCU33组未发生改变,但在PCU67和PCU100组显著升高(P=0.02)。随Optigen替代水平的升高,血浆尿素氮呈线性上升趋势(P=0.09)。与PCUO组相比,PCU33和PCU67组的血浆总蛋白水平并未改变,但PCU100组的血浆总蛋白水平最低(P=0.02)。试验表明舍饲羔羊日粮可用部分Optigen代替豆粕,当替代比例为33%时,对于以40%玉米秸秆为粗料的舍饲羔羊的生长性能和血液生化指标无不利影响。更多还原

【Abstract】 Three experiments were conducted to investigate the effects of polymer coated urea and sodium bentonite on sheep fed corn stalk as basal roughages diet, therefore three experiments has been done. Experiment1:Four ruminally cannulated Dorper x thin-tailed Han crossbred wethers were used in a4x4Latin square design experiment to evaluate the effect of polymer-coated urea (Optigen II) and sodium bentonite (SB) on intake, nutrient digestibility, nitrogen retention, rumen fermentation and microbial nitrogen production in sheep fed high levels of corn stalk. Wethers were housed in an enclosed, climate-controlled room in individual pens. Each period lasted24days(d) with14d of diet adaptation and10d of sampling (5d for digestibility and1d of rest before rumen fluid sampling to prevent interference with the digestibility trial,1d for rumen fluid collection, and3d for the in situ trial). Four days prior to the digestibility trial, animals were placed in individual metabolism cages and allowed to adapt to their cages.Four isonitrogenous and isocaloric diets were formulated with60%corn stalk and40%concentrate (DM basis). The control diet (CON) consisted of barley, wheat bran, and soybean meal, the polymer-coated urea diet (PCU) consisted of barley, wheat bran, corn, and Optigen (soybean meal replaced by Optigen), and the SB diet (SB) was comprised of the control diets supplemented with2%SB, and the PCUSB diet was based on the PCU diet with an additional2%SB. Data were analyzed by analysis of variance for a4x4Latin square design using the MIXED procedure from SAS (1999) with variance components and a covariance structure Sheep on PCU treatment showed a greater OM digestibility (P=0.03), true OM digestibility (P=0.04) compared to CON and SB treatment. Nitrogen digestibility in PCU was greater (P<0.01) compared to CON, SB and PCUSB treatments, also it was higher in SB and PCUSB than CON, but digestibility of other nutrients and DMI did not change. SB did not alter nutrient digestibility except for nitrogen. Dietary treatments did not affect nitrogen intake, or its urinary excretion, but fecal N tended to be lower (P=0.09) for PCU. Nitrogen retention tended to increase (P=0.09) in sheep fed Optigen. Moreover, urinary purine derivatives (PD) and ruminal microbial nitrogen production were not influenced by treatments. Ruminal propionate proportions were increased (P<0.01) in diets that included Optigen, but an addition of SB to Optigen did not alter the ratios. The values of ruminal pH and total VFA were also not influenced by treatments. Ruminal NH3-N levels in PCU continuously increased, with the highest level achieved3h after feeding, and sustained for up to7h. Ruminal DM disappearance of corn stalk increased in PCU and SB treatments compared to CON at24h, was greater than CON or PCUSB at48h (P<0.01), but was lowest at72h for the CON treatment (P<0.05). The effective degradability (ED) of corn stalk DM increased in PCU and SB (P<0.05). Therefore, using Optigen as a source of non-protein nitrogen (NPN) to replace soybean meal in sheep fed high levels of corn stalk improved the digestibility of OM, nitrogen, and ED of corn stalk DM. Although SB improved ED of corn stalk DM, it had no effect on nutrient digestibility except for nitrogen. Adding SB to Optigen had no beneficial effects on nutrient digestibility, nitrogen retention, microbial nitrogen, or rumen fermentation and ED of corn stalk DM.Experiment2:This experiment was designed as same as Expt.1, but the ratio of concentrate to roughages changed to60:40. Four isonitrogenous and isocaloric diets consisting of60%concentrate and40%corn stalk (dry matter basis) were formulated. Apparent digestibility of OM tended to be lower (P=0.06) for sheep on the SB and PCUSB diets. True OM digestibility and N digestibility was lower (P=0.04and0.02, respectively) for SB treatment than other treatments. N retention and ruminal microbial nitrogen production were lower (P=0.03) in SB or PCUSB-fed sheep than that of CON. Ruminal NH3-N concentration was decreased in SB-fed sheep (P=0.03) compared to other treatments. The ruminal concentration of total VFA tended to be greater (P=0.052) in PCUSB-fed sheep than CON. PCUSB treatment decreased the ruminal concentration of acetate (P=0.03) and the ratio of acetate to propionate (P=0.01), but increased the ruminal concentration of propionate (P=0.02) and valerate (P<0.02) when compared with the other treatments. Ruminal NH3-N concentrations in PCU continuously increased, with a peak level achieved3h after feeding, and sustained for up to9h. replacing soybean meal with Optigen for sheep fed high levels of concentrate had no adverse effects on nutrient digestibility, microbial nitrogen, rumen fermentation and ED of corn stalk DM. However, adding SB to Optigen had no beneficial effects on nutrients digestibility, N retention, microbial N and ED of corn stalk DM.Experiment3:The objective of this experiment was to evaluate the effects of replacing different levels of soybean meal by Optigen II on feed intake, growth performance and blood parameters of fattening lambs. Sixty-four Dorper x thin-tailed Han crossbred lambs were blocked by BW [27±3.3(s.d.) kg] and allocated in a randomized complete block design to4treatments. Each treatment had4pens with4lambs per pen. The treatments were control (PCUO), PCU33, PCU67, and PCU100with0,33%,67%, and100%substitution rate of soybean meal nitrogen by Optigen II (DM basis), respectively. Four isonitrogenous (CP=13.5%) and isocaloric (ME=8.2Mj/Kg) dietary treatments contained60%concentrate and40%corn stalk (DM basis) and were offered ad libitum as TMR to ensure approximately5%ort. Lambs were fed56d after14d adaptations twice daily in two equal portions at7:00and19:00h. Data were analyzed as a RCBD using the GLM procedure of SAS (pen was as the experimental unit). Substitution of33and67%of soybean meal nitrogen with Optigen had no effects on DMI, but PCU100significantly decreased DMI (P=0.04). There was no difference in average daily gains (ADG) between PCU33and CON. ADG were significantly decreased by increasing dietary Optigen (P<0.01). The ratio of gain to feed (G/F) was not influenced by replacing33%of soybean meal nitrogen with Optigen, but G/F was decreased (P=0.02) in PCU67or PCU100compared to CON. Blood urea nitrogen tended to linearly increase (P=0.09) with increasing Optigen in the diet. Substitution of33and67%of soybean meal nitrogen by Optigen had no effect on plasma total protein, but it was lowest (P=0.02) in PCU100. The results showed that soybean meal could be partly replaced by Optigen in the diet of feedlot lambs. Substitution of33%soybean meal nitrogen by Optigen had no negative effects on growth performance or blood parameters in feedlot lambs fed diets containing40%corn stalk.更多还原